(1) Field of the Invention
The present invention relates to an image processing method used in resolution enhancement (enlargement) of an image signal.
(2) Description of the Related Art
Conventionally, as a method for resolution enhancement (enlargement) of an image signal, a method for using a fractal coding technique has been proposed (for example, refer to Japanese Patent Publication No. 2000-312294). In this method, a set of fractal parameters of image data of 8×8 pixels in an input image is detected first. After that, the fractal image data of 16×16 pixels is generated using the set of fractal parameters. Further, the 8×8 pixel image data is cut out from the input image, and the 16×16 pixel image data is cut out from the fractal image, and then the respective 8×8 pixel image data and 16×16 pixel image data are subjected to Discrete Cosine Transform (DCT). These two DCT coefficient matrixes are synthesized, and subjected to Inverse Discrete Cosine Transform so as to generate a resolution-enhanced (enlarged) image.
However, in the above-described conventional method, the processing of generating an enlarged image of 16×16 pixel block using the set of fractal parameters detected in the 8×8 pixel block is executed independently on a block-by-block basis. This makes it possible to perform high fidelity resolution transformation of each block. However, since the continuity around the boundaries of blocks is not considered in the transformation, it is likely to occur a phenomenon where the boundaries of adjacent blocks are visually detected.